From d4f2ba2263028ba379ade2dfda64ea221e682e60 Mon Sep 17 00:00:00 2001
From: Martin Joiner <martin@care-planner.co.uk>
Date: Tue, 31 Jan 2023 16:46:56 +0000
Subject: [PATCH] PathFinder: Adding filtering of placeholder routes scored by
 matching parts count

---
 src/PSR7/OperationAddress.php | 20 ++++++++++++-
 src/PSR7/PathFinder.php       | 53 +++++++++++++++++++++++++++++++++++
 tests/PSR7/PathFinderTest.php | 53 +++++++++++++++++++++++++++++++++++
 3 files changed, 125 insertions(+), 1 deletion(-)

diff --git a/src/PSR7/OperationAddress.php b/src/PSR7/OperationAddress.php
index 0ec96e37..c71ac29a 100644
--- a/src/PSR7/OperationAddress.php
+++ b/src/PSR7/OperationAddress.php
@@ -62,7 +62,25 @@ public function path(): string
 
     public function hasPlaceholders(): bool
     {
-        return preg_match(self::PATH_PLACEHOLDER, $this->path()) === 1;
+        return (bool) $this->countPlaceholders();
+    }
+
+    public function countPlaceholders(): int
+    {
+        return preg_match_all(self::PATH_PLACEHOLDER, $this->path()) ?? 0;
+    }
+
+    public function countExactMatchParts(string $comparisonPath): int
+    {
+        $comparisonPathParts = explode('/', trim($comparisonPath, '/'));
+        $pathParts = explode('/', trim($this->path(), '/'));
+        $exactMatchCount = 0;
+        foreach($comparisonPathParts as $key => $comparisonPathPart) {
+            if ($comparisonPathPart === $pathParts[$key]) {
+                $exactMatchCount++;
+            }
+        }
+        return $exactMatchCount;
     }
 
     /**
diff --git a/src/PSR7/PathFinder.php b/src/PSR7/PathFinder.php
index 00ab1929..2ea4c1fe 100644
--- a/src/PSR7/PathFinder.php
+++ b/src/PSR7/PathFinder.php
@@ -206,6 +206,59 @@ private function prioritizeStaticPaths(array $paths): array
             return 0;
         });
 
+        return $this->attemptNarrowDown($paths);
+    }
+
+    /**
+     * Some paths are more static than others.
+     *
+     * @param OperationAddress[] $paths
+     *
+     * @return OperationAddress[]
+     */
+    private function attemptNarrowDown(array $paths): array
+    {
+        if (count($paths) === 1) {
+            return $paths;
+        }
+
+        $partCounts = [];
+        $placeholderCounts = [];
+        foreach ($paths as $path) {
+            $partCounts[] = $this->countParts($path->path());
+            $placeholderCounts[] = $path->countPlaceholders();
+        }
+        $partCounts[] = $this->countParts($this->path);
+        if (count(array_unique($partCounts)) === 1 && count(array_unique($placeholderCounts)) > 1) {
+            // All paths have the same number of parts but there are differing placeholder counts. We can narrow down!
+            return $this->filterToHighestExactMatchingParts($paths);
+        }
+
         return $paths;
     }
+
+    /**
+     * Scores all paths by how many parts match exactly with $this->path and returns only the highest scoring group
+     *
+     * @param OperationAddress[] $paths
+     *
+     * @return OperationAddress[]
+     */
+    private function filterToHighestExactMatchingParts(array $paths): array
+    {
+        $scoredCandidates = [];
+        foreach ($paths as $candidate) {
+            $score = $candidate->countExactMatchParts($this->path);
+            $scoredCandidates[$score][] = $candidate;
+        }
+
+        $highestScoreKey = max(array_keys($scoredCandidates));
+
+        return $scoredCandidates[$highestScoreKey];
+    }
+
+    private function countParts(string $path): int
+    {
+        return preg_match_all('#/#', trim($path, '/')) + 1;
+    }
 }
diff --git a/tests/PSR7/PathFinderTest.php b/tests/PSR7/PathFinderTest.php
index 36d95765..8f42cd2c 100644
--- a/tests/PSR7/PathFinderTest.php
+++ b/tests/PSR7/PathFinderTest.php
@@ -116,4 +116,57 @@ public function testItFindsMatchingOperationForMultipleServersWithSamePath(): vo
         $this->assertCount(1, $opAddrs);
         $this->assertEquals('/products/{id}', $opAddrs[0]->path());
     }
+
+    public function testItPrioritisesOperatorsThatAreMoreStatic(): void
+    {
+        $spec = <<<SPEC
+openapi: "3.0.0"
+info:
+  title: Uber API
+  description: Move your app forward with the Uber API
+  version: "1.0.0"
+paths:
+  /products/{product}/images/{image}:
+    get:
+      summary: A specific image for a specific product
+  /products/{product}/images/thumbnails:
+    get:
+      summary: All thumbnail images for a specific product
+SPEC;
+
+        $pathFinder = new PathFinder(Reader::readFromYaml($spec), '/products/10/images/thumbnails', 'get');
+        $opAddrs    = $pathFinder->search();
+
+        $this->assertCount(1, $opAddrs);
+        $this->assertEquals('/products/{product}/images/thumbnails', $opAddrs[0]->path());
+    }
+
+    public function testItPrioritises2EquallyDynamicPaths(): void
+    {
+        $spec = <<<SPEC
+openapi: "3.0.0"
+info:
+  title: Uber API
+  description: Move your app forward with the Uber API
+  version: "1.0.0"
+paths:
+  /products/{product}/images/{image}/{size}:
+    get:
+      summary: A specific image for a specific product
+  /products/{product}/images/thumbnails/{size}:
+    get:
+      summary: All thumbnail images for a specific product
+  /products/{product}/images/{image}/primary:
+    get:
+      summary: All thumbnail images for a specific product
+SPEC;
+
+        $pathFinder = new PathFinder(Reader::readFromYaml($spec), '/products/10/images/thumbnails/primary', 'get');
+        $opAddrs    = $pathFinder->search();
+
+        $this->assertCount(2, $opAddrs);
+        $this->assertEquals('/products/{product}/images/thumbnails/{size}', $opAddrs[0]->path());
+        $this->assertEquals('/products/{product}/images/{image}/primary', $opAddrs[1]->path());
+    }
+
 }